The majority of these known glioblastoma-secreted factors are cytokines, and many of these function as chemo-attractants, such as C-X3-C motif chemokine (CX3C) ligand 1 (CX3CL1), C-C motif chemokine ligand (CCL) 2 (CCL2), macrophage inhibitory cytokine-1 (MIC-1), and colony-stimulating factor 1 (CSF1) [45,46,47]. The gene discussed is CCL2; the disease is glioblastoma.